The invention concerns an electric lighting lamp with an insulating casing enclosing a parabolic reflector, an electric bulb electrically connected to a power source through a switch, and a common or single control means for the switch and lighting adjustment by adjusting the focus as a result of relative translation between bulb and reflector, said casing being subdivided into a first sub-assembly consisting of the reflector rigidly joined to a rotational adjustment collar, and a second sub-assembly supporting the electric bulb and the switch, the two sub-assemblies cooperating to cause relative displacement when the collar is actuated.
French Pat. No. 1,430,456 and West German Pat. No. 839,838 each describe a lighting lamp which comprises a common means to adjust the focus and control the switch. The switch includes a rotational control which renders the structure of the common control means complex. In French Pat. No. 2,372,382, the switch consists of the translational bulb holder which can be applied against a stationary contact due to reflector displacement.